Apparatus for casting alkaline earth metals



BY 3 a ATTORNEY.

De c. 1, 1931.

H. S. COOPER APPARATUS FOR CASTING ALKALINE EARTH METALS Filed Dec. 10.1928 1 a v z v a 9 42/2/ 7 o M INVENTOlf,

Patented Dec. 1, 1.931

UNITED STATESPAT'ENT OFFICE HUGH S. COOPER, OF CLEVELAND, OHIO, ASSIGNORTO KEMET LABORATORIES COMPANY, INC., A CORPORATION OF NEW YORK APPARATUSFOR CASTING ALKALINE EARTH METALS Application filed December 10, 1928.Serial No. 325,022.

This invention relates to apparatus for casting alkaline earth metals ina purified condition and especially to the casting of purified bariumand strontium and the alloys thereof free from a material content ofoxides, nitrides or hydrides. p

The presence of oxides, nitrides and hydrides in barium and strontiumdeleteriously affects their malleability and ductility. For exampleextremely small amounts of these impurities cause a brittleness whichwill prevent the production of wire in considerable lengths. In themanufacture of these metals into wire of a commercial grade it iseconomically important that the metals from which the wire is made beproduced in a malleable and ductile state, and also in an elongatedhomogeneous mass, so that a minimum of waste will be encountered whenthe metals are drawn into the form of wire or ribbon.

Due to the extreme activity of these metals it has been diflicult tocast them in the proper state and form for making wire or ribbon,because during the process of melting and casting they react with theoxygen and nitrogen of the air to form the deleterious oxides andnitrides.

Therefore one of the objects of my invention is to produce a purifiedmetal in a convenient and workable form.

One embodiment of my invention is illustrated in the accompanyingdrawing. The single figure shown therein is a view, partly in sectionand partly in elevation, of. a device constructed in accordancetherewith.

Acrucible 1, is supported in a suitable manner as here shown by a frame2. The crucible has a flange 3, to which a similar flange 4, of a mold5, is secured by means of screws 6. The mold has a funnel shaped mouth 7leading-into a deep tapered cavity 8, which is closed at its outer endby a removable screw plug 9. The crucible and the mold are preferablymade of iron or nickel,

but they may be made of other metals.

. The crucible and the mold form a chamber from which the air may beexhausted and from which the exterior air may be excluded. no This maybe accomplished by employing one of the gases of the argon group toscavenge the air from the chamber and then maintaining therein anatmosphere of one of said gases at a pressure greater than the exteriorair pressure.

To accomplish this purpose I have shown a tank 10, containing one of thecompressed gases of the above named group, preferably argon. The tank isconnected to the interior of the crucible by means of a flexible o tube11. One end of the tube is connected to the outlet of the valve 12,which controls the flow of the gas from the tank, .and the other end ofthe tube is connected to a nipple 13. The nipple is connected to theinterior of 5 the chamber to provide an inlet for the gas.

A nipple 14, is connected to the interior of the crucible to provide anoutlet for the air and gas scavenged from the chamber. A valve 15. isconnected to the nipple 14, to control the escape of gaseous fluidthrough the nipple.

The crucible is supported in the frame 2, by the nipples 13 and 14,which perform the function of an axis about which the crucible 7, may berevolved, for the purpose of pouring the contents of the crucible intothe mold.

The charge capacity of the crucible is limited by the level of the gasinlet and outlet. The capacity of the mold is proportioned in accordancewith the limited charge capacity of the crucible so that when the meltedcharge is poured from the crucible into the mold, the poured level willbe below the gas inlet and outlet, as indicated by the dotted line inthe drawing.

In this form of the apparatus'the pressure within the chamber ismaintained greater than that on the exterior. Therefore it is notnecessary that the joints of the cham- 1m ber be made air ti zzht inorder to exclude the air from the chamber but it would be desirable whenpracticable in order to conserve the gas supply.

While 1 prefer the above means for ex hausting'and excluding the airfromtbechamher an alternative means may be employed in which a vacuumproducing means (not shown) may be connected to one of the nipples todraw the air from the chamber while- 1 nitrides and hydrides.

In the operation of my preferred form of apparatus the crucible ischarged with the metal to a level just below the nipples. The valve 12,is opened to permit the gas to fiow from the tank into the crucible andscavenge air from the chamber.

The air is driven out through the nipple 14:, and the open valve 15, tothe atmosphere.

After the chamber has been thoroughly scavenged of air the valve 15, maybe closed or it may be left partially open to allow a continuous flow ofgas from the tank through the chamber. The valves 12 and 15, should beso regulated as to maintain a pressurewithinthe chamber greater thanthat on the outside.

The material in the crucible is heated by any suitable means, until themetal becomes molten. Such impuritiesas the oxides,'nitrides andhydrides of the metals, being lighter than the molten metals, andinfusible side of the crucible.

at the temperature of the molten metal, will rise to the surface of themetal and collect as a scum. The edge of the scum adheres to theThecrucible is then in-' verted or tilted to allow the molten metal toflow into the mold.

The impurities remain clinging to the sides of the crucible and themouth of the mold free from the metal in the mold. After the ingot hascooled and hardened the mold is removed from the crucible. The ingot maythen be removed from the mold. If necessary the screw plug is alsoremoved to facilitate the removal of the ingot, by the ins'ertion of apunch through the plug hole.

While I have shown the mold secured to the crucible in an invertedposition directly above it I do not wish to be limited to thisparticular construction, as other modifications of this apparatus may bemade within the scope of my invention. For example, it is within thescope of my invention to secure the mold to the crucible in any desiredangle so that their interiors form a single chamber and that the metalmay be poured from the crucible into the mold by tilting the former.

I claim:

' .1. An apparatus for casting reactive metals, comprising a crucible, amold having its open end detachably secured to the open end of thecrucible to form a closed chamber, a

gas inlet and outlet for said chamber and means for replacing theatmosphere of said chamber with an inert gaseous medium, and means fortilting the crucible and the mold to pour the contents of the crucibleinto the mold.

als, comprising a metal crucible, an inverted metal mold having its openend detachably secured to the opened end of the crucible to form aclosed chamber, a gas inlet and outlet for the chamber, means forsupplying an inert gas under pressure to said inlet and means forcontrolling the entrance of said gas through said inlet and its exitthrough said outlet, and means for inverting the crucible and the moldto pour the contents of the crucible into the mold.

3. An apparatus for casting reactive metals, comprising a cruciblehaving two diametrically opposed trunnions on its outer peripheryprovided with axial openings therethrough communicating with theinterior of the crucible; a support for said crucible having bearingscooperating With said trunnions; a mold having its open end detachablysecured to the open end of said crucible to form a closed chamber; meansfor supplying an inert gaseous medium to said closed chamber through theaxial openings in the trunnions; and'means for rotating the crucible andmold about said trunnions to pour the contents of the crucible into themold.

4. In an apparatus for casting reactive metals, comprising a metalcrucible having two diametrically opposed trunnions on its outerperiphery provided with axial openings therethrough forming a gas inletand outlet for the interior of the crucible, a support for said cruciblehaving bearings cooperating with said trunnions; a mold having a funnelshaped mouth, a projection having a tapered cavity extending from thesmall end of said mouth, and a removable closure member for the smallerextremity of said tapered cavity;

1 means for detachably securing the mouth of the mold to the mouth ofthe crucible to form a closed chamber; means for supplying an inertgaseous medium to the interior of the closed chamber through theopenings of said trunnions to replace the atmosphere of said chamber;control means for said inlet and outlet and means for rotating thecrucible and mold about said trunnions to pour the contents of thecrucible into the mold.

In testimony whereof, I afiix my signature.

HUGH s. COOPER.

2. An apparatus for casting reactive met-

